The use of herbicides and pesticides has proven to be a mixed blessing to mankind. While the value of increased production of food for human consumption has been important in meeting the nutritional needs of the world, the addition of large amounts of herbicidal substances which are often slowly degraded has caused environmental damage. The regulation of use of herbicides to avoid excess dispersal of these active agents into the environment has become an increasing concern to agriculturalists and environmentalists.
The use of dimethylsulfoxide with herbicides has previously been suggested. A study done in 1964 used DMSO with herbicides in solutions containing 0.5 gpa of DMSO to 1 gpa of a mixture containing picloram-2,4-D mixture. Using this large amount of DMSO proved to result in efficacious killing of plants. However, the use of such large amounts of DMSO (33%) in herbicidal compositions has not been practiced, and would undoubtedly be too expensive for widespread use. Furthermore, as indicated in this specification, such concentrations are neither necessary nor advisable.
DMSO has also been used in insecticidal compositions. U.S. Pat. No. 3,321,364 discloses use of DMSO with the insecticide for use in compositions containing ryania. The DMSO is in very small amount and appears to be used primarily as a solubilizing agent.
Keil, of the U.S. Department of Agriculture has suggested use of bacteriocidal and fungicidal compositions containing oxytetracycline and 0.25% to 0.5% DMSO. No use of DMSO in herbicidal compositions is taught therein. Keil suggested that the increased effectiveness was apparently due to the increased absorption and translocation of the active agents.
Robert L. Weintraub has studied the effect of DMSO on plants. He found that aqueous solutions containing 40% or greater amounts of DMSO on cacao seedling caused marginal necroses. It was reported that addition of 0.05% to 15% DMSO to various nutritional supplements such as salts, nutrients, metabolites and dyes resulted in increased absorption.
It has also been reported that use of 10% to 100% DMSO as a solvent enhanced penetration of herbicide to leaves. It goes without saying that use of 10% to 100% DMSO would be prohibitively expensive for use in agricultural application.
It was also reported that use of 1% to 5% DMSO in fungicidal compositions resulted in enhancement of action of some fungicides. No improvement in effect was seen when used with some of the fungicides.